Put it in the well? Dig a mud hole? Drilling rig in place to make holes? Lower filter tube packing? Wash the well? Pipe laying and pipe connection? To fetch/pump water
Release well site
Drilling rig in place, hole formation.
Lower filter tube and packing
Have a good wash
Lower pump and pipeline connection
draw/pump water
Dig a mud pit
1.2 construction preparation
(1) Investigate the distribution (direction and buried depth) of underground pipelines in detail, and seal and block the leaking water source.
⑵ Investigate the rainwater and sewage pipes in the site, remove the silt in the pipes and arrange drainage channels.
(3) Organize project personnel to make safety technical disclosure.
(4) After water and electricity are connected and the site is leveled, materials and equipment will enter the site.
5] Connect water and electricity and install debugging equipment.
[6] Plan the site layout and arrange the drilling rig construction sequence reasonably.
1.3 key points of dewatering well construction
serial number
building technology
Key points of construction
1
Pay-off positioning
According to the design spacing of dewatering wells and the distance from the pit edge, the well location is set out and the cross positioning method is adopted to set out. Due to the large number of underground pipelines on site, 1-2m shall be dug manually before construction, and construction shall be carried out after it is confirmed that there are no underground pipelines.
After positioning, probe the well site. Because the miscellaneous fill on the ground can't be drilled by drilling rig, manual excavation is adopted until it meets the old soil layer.
2
Dig a mud pit
Dig a mud pit near the well site, the size of which is about 6m×6m×0.5m. Multiple wells should be considered when selecting the location of surrounding mud pools. Manually dig a backflow trench between the wellhead and the mud pit. According to the site conditions, a mud pit is dug in the foundation pit 3m away from the dewatering well, and one mud pit is shared by every 1 ~ 3 wells.
three
Dig a pit
In order to remove obstacles under the well site, an exploratory pit with a diameter of 800 mm and a depth of 1.0 ~ 1.5 m should be dug at the well site. When the wellhead soil is loose, casing must be run to avoid hole collapse caused by mud soaking and scouring.
four
Drilling machine hole-forming
Use rotary drilling rig or impact drilling rig to form holes and mud to protect the wall. The completion of this well starts from the ground, and the depth of the well is about 18m. The borehole diameter is Ф 500mm, and the verticality deviation of the well is controlled within 65438 0%. The bottom hole shall be subject to the entry into the 7th layer of strongly weathered mixed granite.
five
Underground pipeline
Sand-free concrete pipe is used for the well pipe of dewatering well, and it is run into the well pipe immediately after the hole is formed. The well pipe is placed on the precast concrete base, with a guide device in the middle of the bottom, and 8 # iron wire tied around it, and slowly lowered. When the difference between the nozzle and the wellhead is 200mm, the well pipe should be connected well, and the joint should be pasted with glass fiber cloth to avoid squeezing mixed sand to block the well pipe, and the well pipe should be fixed vertically with 2 ~ 4 30mm wide bamboo strips. In order to prevent dislocation of upper and lower joints, the well pipe should be erected in the direction before running. The hanging well pipe should be vertical and kept in the center of the well hole. To prevent rainwater, cement sand or foreign matter from flowing into the well, the well pipe should be 200mm above the ground and the wellhead should be covered.
six
filter material
Fill the filter material immediately after running the completion pipe. The filter material should be evenly filled from the bottom of the hole along the periphery of the hole, and it should be continuous to squeeze the mud out of the hole. When filling the filter material, the height of the filter material should be measured with the filler. When the filling quantity is inconsistent with the theoretical calculation quantity, find out the reason in time. Don't use loader to fill directly, but use shovel to cut to prevent unevenness or impact on the shaft wall.
seven
blush
The air compressor gas lift method is used for well washing, and the bottom hole is blown section by section and layer by layer, and the mud and sand at the bottom hole are blown clean until the water and sand are clean.
eight
Arrange water pipes
Pumping and laying drainage pipe network.
Submersible pump is hung in the well with lead wire, with a distance of 10 meter. Tube-well pumps are respectively connected with pipes with water outlet diameters, and connected with ground drainage pipes. The pumped water flows into the main pipeline near the pit from the branch pipe, and is discharged into the municipal rainwater pipeline after passing through the sedimentation tank. The drainage pipe network adopts steel pipe as the main drainage pipe, the diameter of the drainage pipe is 150 mm, the drainage pipe is arranged outside the dewatering well, a support is set every 5 ~ 8m, and the drainage pipe is placed in the center. A sedimentation tank is set at the joint where the drainage pipe network enters the municipal pipeline. Sedimentation tanks can be made of iron drums. If you use a bricklaying trough, you must plaster it. During earthwork excavation, the groundwater level should be kept at least 1m below the excavation surface, and personnel should be arranged to monitor it regularly.
nine
pumpdown
After the networked pump stops, the pump should be started effectively and reasonably according to the change of water level.
10
Water level observation
Before pumping, observe the static water level twice a day in the morning and evening at the initial stage of pumping, and observe 1 time every day after the water level stabilizes.
1.4 quality inspection standard for dewatering wells
(1) The verticality deviation of the borehole is not more than 65438 0%.
⑵ The well depth shall not be less than the design depth, and the final well diameter shall not be less than the design well diameter.
(3) The deviation of well location shall not be greater than 65438 000 mm. ..
(4) The well pipe must be lowered to the drilling center, and the deviation shall not exceed 20mm. ..
5] The filter material is clean and the silt content meets the design requirements.
1.5 requirements for building materials
(1) The filter material is washed sand or crushed stone with a particle size of 1 ~ 3 mm and a silt content of.
⑵ Well tube is φ400mm cement gravel filter tube, and the bottom 2m is used for sedimentation.
(3) Prepare two water level gauges on site.
1.6 construction technical requirements
(1) 0 ~ 1.5m clay hole sealing shall be carried out after well washing.
(2) Wash the well within 24 hours after completion until the water and sand are clean.
(3) When running the pipe, tie 2 ~ 4 bamboo skins around the well pipe with lead wire to make the well pipe consistent with the hole center.
(4) The filler should be evenly filled around, so that the filter material is evenly distributed around the well pipe.
5] Other requirements shall be implemented according to the usual specifications and requirements, so as to ensure that the groundwater is handled well and meet the requirements of foundation engineering construction.
1.7 Quality Assurance Measures for Dewatering Well Construction
(1) Completion quality control measures
(1) Air compressor should be washed with water and sand.
(2) The aperture is consistent from top to bottom, and the design aperture of tube well is φ500mm.
⑵ Protective measures for dewatering wells
(1) The wellhead shall be provided with a manhole cover to prevent sundries from falling into the well.
(2) When earthwork excavation and slope protection are carried out, the finished product protection disclosure shall be made to the construction personnel.
(3) Drainage control measures
① Start the pump in time after well washing, and select the pump model according to the groundwater flow.
(2) Submersible pumps used for pumping and drainage can only be put into the well after trial operation, and they are supervised by special personnel. If any bad pump is found, it should be replaced and maintained in time.
1.8 drainage scheme
According to the dewatering characteristics of this project, submersible pump is used to pump water in the dewatering well, and it enters the drainage system outside the ground through the drainage pipe. The power of submersible pump is 1.5KW/h, the displacement is 3.0-6.0m3/h, and the lift is 30.0-45.0m The sump in the tank is drained by a sewage pump with a power of 3.0KW/h and a displacement of 6.0-8.0m3/h. ..
The discharged groundwater is discharged into the sewage outlet or collected centrally for washing the land wheel and other production and domestic water. Schematic diagram of precipitation is as follows:
Dewatering well
Dewatering well
Dewatering well
drainpipe
Sewage pipeline or secondary utilization